The study's background information informs: "Studies of the association among age, kidney function, and clinical outcomes have reported that elderly patients are less likely to develop end-stage renal disease (ESRD) compared with younger patients and are more likely to die than to progress to kidney failure even at the lowest levels of estimated glomerular filtration rate [eGFR; flow rate of filtered fluid through a kidney]."
Kidney failure has been defined in earlier research as receiving long-term dialysis. This not only reflects the disease's progression, it also plays a role in deciding the treatment. "Because it is plausible that the likelihood of initiating long-term dialysis among individuals with kidney failure varies by age, earlier studies may provide an incomplete picture of the burden of advanced kidney disease in older adults, based on the incidence of long-term dialysis alone."
In a study to determine whether age is linked to the likelihood of treated kidney failure, including long-term dialysis or kidney transplantation, untreated kidney failure and all-cause mortality, Brenda R. Hemmelgarn, M.D., Ph.D., from Calgary University in Alberta, Canada and her team assessed 1,816,824 adults in Alberta, who had outpatient eGFR measured with a baseline eGFR of 15 mL/min/1.73 m2 or higher.
The eGFRs were measured between May 2002 and March 2008, and none of the studied subjects required renal replacement therapy at the beginning of the study. The primary outcome measures for the study were defined as adjusted rates of treated kidney failure, untreated kidney failure (progression to eGFR
The findings revealed that 97,451 subjects (5.4%) had died during the average midpoint follow-up of 4.4 years, whilst 3,295 subjects or 0.18% developed treated kidney failure and 3,116 participants or 0.17% developed untreated kidney failure. Furthermore, within each eGFR stratum, the results showed a raise in adjusted mortality rates as the age of the participants increased, and that the rates of treated kidney failure were consistently higher within the youngest age group.
The researchers write:
"For example, in the lowest eGFR stratum (15-29 mL/min/1.73 m2), adjusted rates of treated kidney failure were more than 10-fold higher among the youngest (18-44 years) compared with the oldest (85 years or older) groups."
The results for untreated kidney failure proved to be the opposite, i.e. the risk of untreated kidney failure increased with lower eFGR categories compared with those that were higher, whilst the link was stronger the older the participants became.
The researchers remark: "For the lowest eGFR stratum (15-29 mL/min/1.73 m2), adjusted rates of untreated kidney failure were more than 5-fold higher among the oldest age stratum (85 years or older) compared with the youngest age stratum (18-44 years)."
Overall kidney failure rates, regardless of whether they were treated or untreated, showed less variation across age groups.
According to the researchers, the study results indicate that the incidence of advanced kidney disease in elderly individuals may be significantly underestimated compared with the rates of treated kidney failure alone.
"These findings have important implications for clinical practice and decision making; coupled with the finding that many older adults with advanced chronic kidney disease [CKD] are not adequately prepared for dialysis, these results suggest a need to prioritize the assessment and recognition of CKD progression among older adults.
Our findings also imply that clinicians should offer dialysis to older adults who are likely to benefit from it - and should offer a positive alternative to dialysis in the form of conservative management (including end-of-life care when appropriate) for patients who are unlikely to benefit from (or prefer not to receive) long-term dialysis.
Given the large number of older adults with severe CKD, these results also highlight the need for more proactive identification of older adults with CKD, assessment of their symptom burden, and development of appropriate management strategies. Finally, our study demonstrates the need to better understand the clinical significance of untreated kidney failure, the factors that influence dialysis initiation decisions in older adults, and the importance of a shared decision making process for older adults with advanced CKD."
Wolfgang C. Winkelmayer, M.D., M.P.H., Sc.D., who is also a contributing Editor of JAMA and Manjula Kurella Tamura, M.D., M.P.H., both from California's Stanford University School of Medicine in Palo Alto write in a linked editorial:
"The work by Hemmelgarn and colleagues highlights a potentially sizeable unmeasured burden of untreated kidney failure among older adults. It is of paramount importance to refine the current understanding of what constitutes appropriate treatment for kidney failure, which factors influence the decision-making process, and which methods are optimal for aligning treatment plans with patient goals and prognosis. Finding the right balance between over- treatment and under-treatment is challenging but necessary. This important scientific and ethical debate can no longer be avoided, for both individual and societal good."
Written by Petra Rattue